<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <h2>a.html</h2>

  <iframe src="http://127.0.0.1:5500/postMessage/b.html" frameborder="0" id="iframe"></iframe>

  <script>
    // 给b发送数据
    let iframe = document.getElementById('iframe')
    iframe.onload = function() {
      let data = {
        name: 'Tom'
      }
      iframe.contentWindow.postMessage(JSON.stringify(data), 'http://127.0.0.1:5500')
    }


    // 监听b传过来的数据
    window.addEventListener('message', function(e) {
      console.log(e.data);
    })
  </script>
</body>
</html>